$ cat writeup.md…
$ cat writeup.md…
kalmarctf2026
Task: Hobby OS (Astral OS) kernel exploitation under QEMU with SMEP, patched pread/pwrite. Solution: Find iovec_user_check() bug in readv/writev that skips validation when first iovec has len=0, use pipe-based kernel read/write to overwrite process credentials for privilege escalation.
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